'SUBTLE is THE LORD' 131
In the opening lines of the essay, he asks the reader's forbearance: 'Since I com-
pletely lacked the material for penetrating deeper into the subject, I beg that this
circumstance will not be interpreted as superficiality.'
The main questions raised in the essay are, How does a magnetic field, gen-
erated when a current is turned on, affect the surrounding aether? How, in turn,
does this magnetic field affect the current itself? Evidently Einstein believed in an
aether at that time. He regarded it as an elastic medium and wondered in partic-
ular how 'the three components of elasticity act on the velocity of an aether wave'
which is generated when the current is turned on. He came to the following main
conclusion. 'Above all, it ought to be [experimentally] shown that there exists a
passive resistance to the electric current's ability for generating a magnetic field;
[this resistance] is proportional to the length of the wire and independent of the
cross section and the material of the conductor.' Thus, the young Einstein discov-
ered independently the qualitative properties of self-induction (a term he did not
use). It seems clear that he was not yet familiar with earlier work on this phe-
nomenon. In his paper he mentions 'the wonderful experiments of Hertz.' I do
not know how he became aware of Hertz's work. At any rate, it is evident that at
that time he already knew that light is an electromagnetic phenomenon but did
not yet know Maxwell's papers.
- The Aarau Question. In his final autobiographical note [El2], Einstein
wrote, 'During that year [sometime between October 1895 and the early fall of
1896] in Aarau the question came to me: If one runs after a light wave with [a
velocity equal to the] light velocity, then one would encounter a time-independent
wavefield. However, something like that does not seem to exist! This was the first
juvenile thought experiment which has to do with the special theory of relativity'
(and he added, 'Invention is not the product of logical thought, even though the
final product is tied to a logical structure.'). Also, in his more extensive autobio-
graphical notes, published in 1949, Einstein remarked that 'after ten years of
reflection such a principle [special relativity] resulted from [this] paradox upon
which I had already hit at the age of sixteen' [E6].
- The ETH Student. Since Rudolf Kayser, Einstein's son-in-law and biog-
rapher, was himself not a physicist, it is hard to believe that the following lines
from the biography could have come from anyone but Einstein himself. 'He
encountered at once, in his second year of college [1897-8], the problem of light,
ether and the earth's movement. This problem never left him. He wanted to con-
struct an apparatus which would accurately measure the earth's movement against
the ether. That his intention was that of other important theorists, Einstein did
not yet know. He was at that time unacquainted with the positive contributions,
of some years back, of the great Dutch physicist Hendrik Lorentz, and with the
subsequently famous attempt of Michelson. He wanted to proceed quite empiri-
cally, to suit his scientific feeling of the time, and believed that an apparatus such
as he sought would lead him to the solution of the problem, whose far-reaching
perspectives he already sensed. But there was no chance to build this apparatus.
